Impregnation of fabric for advanced mechanical, transport, and functional properties

Abstract

A method includes a) impregnating a woven, non-woven, or knitted fabric with a silk fibroin solution. A method includes b) curing the silk fibroin solution, thereby forming the cured silk polymer matrix having the woven, non-woven, or knitted fabric embedded therein. The fiber-reinforced polymer composite includes the cured polymer matrix in an amount by weight that is at least 25%, at least 50%, at least 75%, or at least 100% of the woven, non-woven, or knitted fabric. The cured polymer matrix comprises silk fibroin in an amount by weight of at least 10%.

Description

CLAIM TO PRIORITY

[0001] This application claims benefit of and is a continuation of International Patent Application No. PCT / US 2024 / 019386 (Attorney Docket. No. 2095.0597), filed Mar. 11, 2024, and entitled “IMPREGNATION OF FABRIC FOR ADVANCED MECHANICAL, TRANSPORT, AND FUNCTIONAL PROPERTIES,” International Pub. No. WO2024 / 187188, which is hereby incorporated by reference in its entirety for all purposes.

[0002] International Patent Application No. PCT / US2024 / 019386 (Attorney Docket. No. 2095.0597) claims the benefit of the following provisional applications, which are hereby incorporated by reference in their entirety for all purposes: U.S. Patent Application Ser. No. 63 / 489,362, filed Mar. 9, 2023; and U.S. Patent Application Ser. No. 63 / 505,543, filed Jun. 1, 2023.STATEMENT REGARDING FEDERALLY FUNDED RESEARCH

[0003] Not applicable.REFERENCE TO A SEQUENCE LISTING

[0004] Not applicable.BACKGROUND

[0005] The textile and clothing industry is estimated to produce 110 million tons of new textiles every year worldwide and, due to fast fashion, this production volume is constantly increasing together with the generation of textile waste. Globally, textile waste generation amounts to 92 million tons per year—with 17 million tons generated in the US alone—and it is expected to reach 134 million tons by 2030. Despite 95% of textile waste could be reused and recycled, just 15% of it is actually recovered from the waste stream thus making the textile and clothing industry one of the biggest contributors to the generation of a huge amount of waste and green house emission. More specifically, textile production is the second most polluting industry in the world—after the oil industry—accounting for 1.2 billion tons of greenhouse emissions and by 2050 it is estimated it will use up to 25% of the world's carbon budget. In this context, there is an increasing need for strategies that tackle the adverse effects of the textile and clothing industry on the environment and that promote the recovery of textile waste from the landfills giving it a second life through circular economy approaches.

[0006] This disclosure is focused on the impregnation of fabric using silk fibroin solution in order to impart new advanced properties that broaden the field of application of fabric with the aim of recycling and repurposing textile waste. To date, fabric functionalization has been widely used and has been focused on improving properties of fabric such as dyeability, wrinkle resistance, antimicrobial activity, flame retardancy and water resistance. Silk fibroin has been used in the context of fabric functionalization in combination with crosslinking agents to improve cotton wrinkle recovery, with antimicrobial agents to yield antimicrobial textile medical products and with silica nanoparticles to improve dyeability. After these functionalization procedures, fabrics undergo a squeezing and washing step to remove unbound silk fibroin. The interaction between silk fibroin and fabrics as well as its effect on the mechanical, transport and thermal properties is not investigated. In fact, the functionalization of textiles targets the improvement of the performances of new pristine fabric within the textile and clothing industry to fulfil costumer's needs in specific conditions (e.g., personal protective equipment, technical sport clothing) but does not explore fabric recycling and repurpose in other industries. Additionally, functionalized textiles are designed to gain specific functional properties without losing their comfort by compromising their softness and breathability. As a consequence, the enhancement of mechanical properties, barrier properties and shapeability has not been the target of fabric functionalization, which is not meant to expand the applicability of fabrics beyond the textile and clothing industry.

[0007] On the other hand, textiles have been employed as reinforcement in the fabrication of composite materials. In particular, the interest in natural fiber-reinforced composites is rapidly increasing due to their eco-friendly nature, low cost, biodegradability, light weight, and good mechanical properties which enabled their commercial application in the automotive and construction industries. Fiber-reinforced composites show different properties based on fiber geometries and length: discontinuous fibers, continuous aligned fibers and woven or knitted fabrics. Discontinuous randomly oriented fibers offer the advantage of yielding isotropic materials but require carefully designed dispersion techniques to avoid aggregation. Continuous aligned fibers provide maximum tensile strength in the parallel direction to fibers but require complicated fabrication techniques to ensure aligning. Composites with fabrics are easier to fabricate and can be used to obtain quasi-isotropic materials. Fabric reinforcements have been used in the aforementioned industries to improve the mechanical properties of polymeric, ceramic, or cementitious materials as well as in the packaging industries to improve the barrier properties of plastics. In fact, the presence of fibers in the polymeric matrix increases the tortuosity factor for the diffusion of gas molecules, which reduces the permeability. The approach presented here differs from the previously reported studies which use textiles as reinforcement materials focusing on the effect of fibers and fabrics on the properties of the matrix (which is the main component of the composite). Here, the composite materials are mainly constituted by fabric (10 to 45 wt. %) and are shaped using a polymeric material (i.e., silk fibroin) which increases its stiffness and barrier properties rather than vice versa. Among the studies reported in literature, the interaction of knitted fabrics and silk fibroin has not been investigated yet.

[0008] Conventionally, composite materials having fabric as an internal structural material embedded within a cured resin are widely applicable across a range of industries, from medical to automotive. Traditionally, the cured resins in these composite materials are not sustainable and are ecologically unfriendly. Their processing requires the use of potentially hazardous solvents and the resulting products are not readily degradable.

[0009] A need exists for composite materials that can achieve some of the performance capabilities of traditional composite materials, but with a cured resin component that does not suffer from the shortcomings of traditional cured resins.SUMMARY

[0010] Disclosed herein are methods for impregnation of fabric for advanced mechanical, transport and functional properties. In some aspects, the techniques described herein relate to a method of making a fiber-reinforced polymer composite including a cured silk polymer matrix having a woven, non-woven, or knitted fabric embedded therein, the method including: a) impregnating a woven, non-woven, or knitted fabric with a silk fibroin solution; b) curing the silk fibroin solution, thereby forming the cured silk polymer matrix having the woven, non-woven, or knitted fabric embedded therein, wherein the fiber-reinforced polymer composite includes the cured polymer matrix in an amount by weight that is at least 25%, at least 50%, at least 75%, or at least 100% of the woven, non-woven, or knitted fabric, wherein the cured polymer matrix includes silk fibroin in an amount by weight of at least 10%.

[0011] In some aspects, the techniques described herein relate to a method of making a fiber-reinforced silk polymer composite including a cured silk polymer matrix impregnating a woven, non-woven, or knitted fabric substrate, the method including: a) impregnating the woven, non-woven, or knitted fabric with a silk fibroin solution, the woven, non-woven, or knitted fabric having a native porosity of at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%; b) curing the silk fibroin solution, thereby forming the cured silk polymer matrix within the pores of the woven, non-woven, or knitted fabric and producing the fiber-reinforced silk polymer composite, wherein the fiber-reinforced polymer composite has a composite porosity that is at least 50% less than the native porosity of the woven, non-woven, or knitted fabric substrate, wherein the cured polymer matrix includes silk fibroin in an amount by weight of at least 10%.

[0012] These and other systems, methods, objects, features, and advantages of the present disclosure will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings.

[0013] All documents mentioned herein are hereby incorporated in their entirety by reference. References to items in the singular should be understood to include items in the plural, and vice versa, unless explicitly stated otherwise or clear from the text. Grammatical conjunctions are intended to express any and all disjunctive and conjunctive combinations of conjoined clauses, sentences, words, and the like, unless otherwise stated or clear from the context.BRIEF DESCRIPTION OF THE FIGURES

[0014] The disclosure and the following detailed description of certain embodiments thereof may be understood by reference to the following figures:

[0015] FIG. 1 depicts a fabrication method and fiber-reinforced polymer composite according to aspects of the present disclosure.

[0016] FIG. 2 depicts: A) SEM micrographs of the cross section (top) and surface (bottom) of the composite materials. B) Weight of the composite materials varying the concentration of silk fibroin solution. C) Thickness of the composite materials varying the concentration of silk fibroin solution D) Color analysis in the RGB color space. Blue value of the composite materials varying the concentration of silk fibroin solution.

[0017] FIG. 3 depicts thermal and mechanical properties of the composite materials: A) Thermogravimetric analysis. B) Derivative thermogravimetry. C) Differential scanning calorimetry. D) Stress vs. Strain curves. E) Young's modulus. D) Elongation at break.

[0018] FIG. 4 depicts: A) Bending angle of the composite materials. B) Pictures of composite materials molded in various shapes: noodle box (left) cups (top right) corrugated cardboard (bottom right). C) Imprinting of diffraction grating on the composite materials. Macroscopic picture (left) SEM micrographs (right).

[0019] FIG. 5 depicts mechanical properties of the recycled composites: A) Tensile Strength B) Young's modulus. C) Elongation at break.

[0020] FIG. 6 depicts sensors including: A) Temperature sensor. B) Cold chain monitoring. C) Oxygen Sensor.

[0021] FIG. 7A and FIG. 7B depict an increase in silk fibroin solution concentration corresponding to a linear increase in Young's Modulus and composites with higher tensile strength.

[0022] FIG. 7C depicts twills with various increasing silk fibroin concentrations that resulted in the data presented in FIG. 7A and FIG. 7B.

[0023] FIG. 8 depicts a mechanical characterization (Youngs modulus [GPa] vs / Tensile strength [Mpa]) of various materials including twill-silk fibroin composites.

[0024] FIG. 9A shows that an increase in silk fibroin solution concentration corresponds to a decrease in bending angle and FIG. 9B presents images of the materials tested in FIG. 9A.DETAILED DESCRIPTION

[0025] Before the present disclosure is described in further detail, it is to be understood that the disclosure is not limited to the particular embodiments described. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The scope of the present disclosure will be limited only by the claims. As used herein, the singular forms “a”, “an”, and “the” include plural embodiments unless the context clearly dictates otherwise.

[0026] It should be apparent to those skilled in the art that many additional modifications besides those already described are possible without departing from the inventive concepts. In interpreting this disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. Variations of the term “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, so the referenced elements, components, or steps may be combined with other elements, components, or steps that are not expressly referenced. Embodiments referenced as “comprising” certain elements are also contemplated as “consisting essentially of” and “consisting of” those elements. When two or more ranges for a particular value are recited, this disclosure contemplates all combinations of the upper and lower bounds of those ranges that are not explicitly recited. For example, recitation of a value of between 1 and 10 or between 2 and 9 also contemplates a value of between 1 and 9 or between 2 and 10.

[0027] As used herein, “silk fibroin” refers to silk fibroin protein whether produced by silkworm, spider, or other insect, or otherwise generated (Lucas et al., Adv. Protein Chem., 13: 107-242 (1958)). Any type of silk fibroin can be used in different embodiments described herein. Silk fibroin produced by silkworms, such as Bombyx mori, is the most common and represents an earth-friendly, renewable resource. For instance, silk fibroin used in a silk film may be attained by extracting sericin from the cocoons of B. mori. Organic silkworm cocoons are also commercially available. There are many different silks, however, including spider silk (e.g., obtained from Nephila clavipes), transgenic silks, genetically engineered silks, such as silks from bacteria, yeast, mammalian cells, transgenic animals, or transgenic plants, and variants thereof, that can be used. See, e.g., WO 97 / 08315 and U.S. Pat. No. 5,245,012, each of which is incorporated herein by reference in their entireties.

[0028] The interaction between silk fibroin and fabrics—new and recycled—can be realized by impregnation to yield advanced properties (e.g., mechanical, transport, sensing) that broaden the field of application of fabrics with the aim of addressing real-life problems. Without wishing to be bound by any particular theory, it is thought that silk fibroin can be used to modify the mechanical properties of fabric, imparting stiffness and shapeability, as well as to improve its barrier properties, modulating the permeability to oxygen and water vapor. By doing so, textile waste can be functionalized and molded with the long-term goal of being recovered from the waste stream and being repurposed in other industries. As an example, using this approach, recovered fabrics could be converted into packaging materials with the double advantage of reducing both plastic packaging waste and textile waste.

[0029] Methods described herein differ from previously reported fabric functionalization methods which focus on the improvement of fabric performance within the textile and clothing industry, but do not target their recycling and repurpose in other fields. At the same time, this approach also differs from the use of textiles as reinforcement materials for polymeric and cementitious matrices. Here, fabric is the main component and is shaped using a polymeric material (i.e., silk fibroin) which dictates its stiffness and barrier properties rather than vice versa.

[0030] Thus, the disclosure herein includes: the characterization of the effect of silk fibroin on the properties of fabric; the study of the recyclability of fabric / silk fibroin composites; and their advanced functionalization for the developments of colorimetric sensors that employ fabric / silk fibroin composites as substrate and stabilizing agents. With respect to fabrication and characterization of fabric / silk fibroin composites, disclosed herein are composite materials using silk fibroin (aqueous solution) to modify the surface and bulk of fabrics (solid) and characterize the effect of silk fibroin on their properties. In embodiments, fabric may be infiltrated with silk fibroin solutions at various concentrations yielding composites materials with a broad range of compositions and properties that may be characterized by evaluating the influence of silk fibroin on the macroscopic and microscopic morphology, thermal properties, tensile properties, stiffness, wettability and transport properties. Additionally, the shapability of the materials can be studied both at the macro and micro scale. With respect to the investigation of the recyclability of the fabric / silk fibroin composite materials, the feasibility of closed-loop recycling of the composite materials is disclosed. Silk fibroin may be removed from the composite to re-obtain the pristine fabric, such fabric may be infiltrated once again with silk fibroin to yield a new composite. This cycle may be repeated several times (e.g., 5 cycles) and the properties of the recycled composite can be evaluated after each cycle, in particular, the variation of the mechanical and transport properties. With respect to the functionalization of fabric / silk fibroin composite materials to confer functional sensing properties, disclosed herein are colorimetric sensing inks (e.g., temperature, cold chain, and oxygen sensors) that may be printed on the fabric either before the infiltration with silk fibroin or directly on the composite materials. Silk may also be used as a stabilizing agent for the labile molecules used for sensing.

[0031] With reference to FIG. 1, a method 100 of making a fiber-reinforced polymer composite 150 comprising a cured silk polymer matrix having a woven, non-woven, or knitted fabric embedded therein according to the present disclosure may include (a) impregnating the woven, non-woven, or knitted fabric 120 with a silk fibroin solution 110, and (b) curing the silk fibroin solution 110, thereby forming the cured silk polymer matrix having the woven, non-woven, or knitted fabric 120 embedded therein.

[0032] Adoption of silk as a resin for fabric (and other large-scale objects) in alternative to petrochemically-derived binders is a highly unexpected use. The inventors surprisingly discovered that an impressive range of material properties could be achieved by the fiber-reinforced polymer composite 150. Without wishing to be bound by any particular theory, the pursuit of sustainable replacements for conventional polymers and resins has historically been a challenging pursuit that has been met with more failures than successes, so the baseline likelihood of success is low, and achievement of performance that approaches the performance of conventional polymers using sustainable replacements is highly unexpected. The conventional use of silk as a textile makes it a particularly good binder for the transformation of textile waste into a molded object, for example, because of its ability to unite the material universe of textiles while adding structural properties that are germane to regenerated silk fibroin solution use and polymorphic transformation.

[0033] In some aspects, the fiber-reinforced polymer composite 150 may include the cured silk polymer matrix in an amount by weight of at least 20% of the woven, non-woven, or knitted fabric. For example, the silk fibroin content of the fiber-reinforced polymer composite may be an amount by weight of at least 20% of the woven, non-woven, or knitted fabric after curing (e.g., when the fiber-reinforced polymer composite is dry), which in some embodiments may provide good results. However, embodiments are not limited thereto, and in some aspects, the fiber-reinforced polymer composite includes the cured polymer matrix in an amount by weight that is at least 25% of the woven, non-woven, or knitted fabric, at least 50% of the woven, non-woven, or knotted fabric, at least 75% of the woven, non-woven, or knitted fabric, or at least 100% of the woven, non-woven, or knitted fabric, with each range providing various advantages thereto.

[0034] In some aspects, the cured (e.g., dry) polymer matrix may include silk fibroin in an amount by weight of at least 10%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 10% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 30% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 50% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 70% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 90% and 100%.

[0035] A method of making a fiber-reinforced silk polymer composite 150 comprising a cured silk polymer matrix impregnating a woven, non-woven, or knitted fabric substrate according to some aspects may include (a) impregnating the woven, non-woven, or knitted fabric 120 with a silk fibroin solution 110. In some aspects, the woven, non-woven, or knitted fabric 120 may have a native porosity of at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%, with each range providing various advantages thereto.

[0036] A method according to some aspects may further include (b) curing the silk fibroin solution, thereby forming the cured silk polymer matrix within the pores of the woven, non-woven, or knitted fabric and producing the fiber-reinforced silk polymer composite. In some aspects, the fiber-reinforced polymer composite may have a composite porosity that is at least 50% less than the native porosity of the woven, non-woven, or knitted fabric substrate. Furthermore, in some aspects, the cured polymer matrix may include silk fibroin in an amount by weight of at least 10%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 10% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 30% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 50% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 70% and 100%. In some cases, the cured polymer matrix includes silk fibroin in an amount by weight of between 90% and 100%.

[0037] In some aspects, the silk fibroin solution may include silk fibroin in an amount by weight of between 0.1% and 30%. In some cases, advantageous results are achieved when the silk fibroin solution includes silk fibroin in an amount by weight of between 10% and 30%, such as impressive mechanical rigidity. In some cases, advantageous results are achieved when the silk fibroin solution includes silk fibroin in an amount by weight of between 0.1% and 10%, such as enhanced tensile properties.

[0038] In some aspects, the woven, non-woven, or knitted fabric and the silk fibroin solution may be in a mold having a negative imprint of a shape during the curing of the silk fibroin solution (e.g., of step b). The fiber-reinforced polymer composite may thereby take a solid form including at least a portion of the shape.

[0039] In some aspects, the shape may be a cup, a box, a corrugated sheet, or a combination thereof.

[0040] In some aspects, the mold may have a negative imprint of a micropattern, thereby providing the micropattern on at least a portion of a surface of the fiber-reinforced polymer composite.

[0041] In some aspects, the impregnating (e.g., of step a) may be performed at an impregnating pressure of 1 atm. However, embodiments are not limited thereto, and in some examples, the impregnating may be performed at an impregnating pressure range of between 0.1 atm and 20 atm, between 0.2 atm and 10 atm, or between 0.5 atm and 5 atm. In some cases, the impregnating pressure can be between 0.1 atm and 20 atm. In some cases, the impregnating pressure can be between 0.2 atm and 10 atm. In some cases, the impregnating pressure can be between 0.5 atm and 5 atm.

[0042] In some aspects, the impregnating (e.g., of step a) may be performed at an impregnating temperature of between 4° C. and 50° C., between 10° C. and 40° C., or between 18° C. and 25° C., with each range providing various advantages thereto. In some cases, the impregnating temperature can be between 4° C. and 50° C. In some cases, the impregnating temperature can be between 10° C. and 40° C. In some cases, the impregnating temperature can be between 18° C. and 25° C.

[0043] In some aspects, the curing (e.g., of step b) may be performed at a curing pressure of between 0.1 MPa and 50 MPa, between 4 MPa and 40 MPa, or between 10 MPa and 30 MPa, with each range providing various advantages thereto. In some cases, the curing pressure can be between 0.1 MPa and 50 Mpa. In some cases, the curing pressure can be between 4 MPa and 40 Mpa. In some cases, the curing pressure can be between 10 MPa and 30 Mpa.

[0044] In some aspects, the curing (e.g., of step b) may be performed at a curing temperature of between 18° C. and 250° C., between 60° C. and 200° C., or between 120° C. and 180° C., with each range providing various advantages thereto. In some cases, the curing temperature can be between 18° C. and 250° C. In some cases, the curing temperature can be between 60° C. and 200° C. In some cases, the curing temperature can be between 120° C. and 180° C.

[0045] In some aspects, the curing (e.g., of step b) may be performed at a curing relative humidity of between 0% and 90%, between 10% and 60%, or between 20% and 40%, with each range providing various advantages thereto. In some cases, the curing relative humidity can be between 0% and 90%. In some cases, the curing relative humidity can be between 10% and 60%. In some cases, the curing relative humidity can be between 20% and 40%.

[0046] In some aspects, the curing (e.g., of step b) may include drying at a curing temperature of between 100° C. and 150° C. a curing pressure of between 20 MPa and 30 MPa, and a curing relative humidity of between 20% and 40%.

[0047] In some aspects, the method may further include micropatterning the fiber-reinforced silk polymer composite.

[0048] In some aspects, the method may further include affixing an embedded functional sensing spot to the woven, non-woven, or knitted fabric prior to impregnating.

[0049] Functional sensing spots as described with reference to some aspects herein (e.g., embedded or external) may include pH, temperature, cold chain monitoring, and impact sensing inks, which provide unexpectedly good results in, e.g., their sensing abilities.

[0050] In some aspects, affixing the embedded functional sensing spot may include printing the embedded functional sensing spot from an embedded functional sensing ink.

[0051] In some aspects, the method may further include affixing an exposed functional sensing spot to the fiber-reinforced silk polymer composite.

[0052] In some aspects, affixing the exposed functional sensing spot may include printing the exposed functional sensing spot from an exposed functional sensing ink.

[0053] In some aspects, a fiber-reinforced silk polymer composite 150 may comprise a cured silk polymer matrix and a woven, non-woven, or knitted fabric 120 embedded within the cured polymer matrix. The fiber-reinforced polymer composite may include the cured polymer matrix in an amount by weight that is equal to or greater than the woven, non-woven, or knitted fabric, and the cured polymer matrix comprises silk fibroin in an amount by weight of at least 10%.

[0054] In some aspects, a fiber-reinforced silk polymer composite 150 may include silk fibroin that penetrates the fabric 120's fiber bundles such that silk may be present among the single fibers of the fabric 120, rather than merely coating external surfaces of the fabric 120.

[0055] In some aspects, a fiber-reinforced silk polymer composite 150 may comprise a woven, non-woven, or knitted fabric substrate. In some aspects, the fabric substrate may have a native porosity (e.g., a macroscopic porosity, rather than referring to the pores within the fibers themselves) of at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%, with each range providing various advantages thereto. In some cases, the native porosity is at least 50%, In some cases, the native porosity is at least 60%. In some cases, the native porosity is at least 70%. In some cases, the native porosity is at least 80%. In some cases, the native porosity is or at least 90%.

[0056] Furthermore, the fiber-reinforced silk polymer composite 150 may include a cured silk polymer matrix impregnating the woven, non-woven, or knitted fabric substrate, where the cured silk polymer matrix may include silk fibroin in an amount by weight of at least 10%. The fiber-reinforced polymer composite 150 may have a composite porosity (e.g., macroscopic) that is at least 50% less than the native porosity of the woven, non-woven, or knitted fabric substrate.

[0057] In some aspects, the woven, non-woven, or knitted fabric 120 may be selected from cotton jersey or other types of fabric such as other types of cotton (canvas, twill, sateen, etc.), linen, silk fabric (organza, crepe, satin, etc.), and combinations thereof. In some aspects, synthetic and semi-synthetic fabrics (e.g., rayon, polyester, nylon, acrylic) may also be used. In an example, the woven, non-woven, or knitted fabric 120 is cotton jersey.

[0058] In some aspects, the cured silk polymer matrix may further include an additive, where the additive may include plasticizers (e.g., glycerol) or crosslinkers for silk (e.g., acids or alcohols), and combinations thereof. Additionally, the additive may include small quantities of antioxidants and / or antimicrobials, which may enhance the functionality of the fiber-reinforced silk polymer composite 150 for packaging applications.

[0059] In some aspects, the fiber-reinforced silk polymer composite 150 may have a thickness of between 0.1 mm and 5 mm. In some aspects, the fiber-reinforced silk polymer composite 150 may have a thickness of between 0.4 mm and 2 mm.

[0060] In some aspects, the fiber-reinforced silk polymer composite 150 may have a tensile strength of between 2 MPa and 80 MPa, between 8 MPa and 40 MPa, or between 10 MPa and 20 MPa. In some cases, the tensile strength can be between 2 MPa and 80 Mpa. In some cases, the tensile strength can be between 8 MPa and 40 Mpa. In some cases, the tensile strength can be between 10 MPa and 20 Mpa.

[0061] In some aspects, the fiber-reinforced silk polymer composite 150 may have an elongation at break of between 0.1% and 800%, between 2% and 400%, or between 20% and 200%. In some cases, the elongation at break can be between 0.1% and 800%. In some cases, the elongation at break can be between 2% and 400%. In some cases, the elongation at break can be between 20% and 200%.

[0062] In some aspects, the fiber-reinforced silk polymer composite 150 may have a Young's modulus of between 0.5 MPa and 20 GPa, between 100 MPa and 10 GPa, or between 200 MPa and 2 GPa. In some cases, the Young's modulus can be between 0.5 MPa and 20 GPa. In some cases, the Young's modulus can be between 100 MPa and 10 GPa. In some cases, the Young's modulus can be between 200 MPa and 2 GPa.

[0063] In some aspects, the fiber-reinforced silk polymer composite 150 may have a material density of between 0.1 g / cm3 and 5 g / cm3, between 0.3 g / cm3 and 2 g / cm3, or between 0.4 g / cm3 and 1 g / cm3 . In some cases, the material density can be between 0.1 g / cm3 and 5 g / cm3 . In some cases, the material density can be between 0.3 g / cm3 and 2 g / cm3. In some cases, the material density can be between 0.4 g / cm3 and 1 g / cm3.

[0064] In some aspects, the fiber-reinforced silk polymer composite 150 may include at least one patterned surface. Furthermore, in some aspects, the at least one patterned surface may include a pattern selected from a diffraction grating, a lotus leaf pattern, a gecko feet pattern, a micro pyramid, a cube, a sphere, or a cone array, and combinations thereof.

[0065] A method of recycling a fiber-reinforced silk polymer composite 150 according to some aspects may comprise dissolving at least a portion of a cured silk polymer matrix impregnating a woven, non-woven, or knitted fabric substrate, and separating the at least a portion of the cured silk polymer matrix from the woven, non-woven, or knitted fabric substrate. In some aspects, the fiber-reinforced silk polymer composite 150 may be a fiber-reinforced silk polymer composite 150 as described and / or made according to the some aspects described herein. In an example embodiment, the dissolving may use a LiBr salt solution.

[0066] Certain logical groupings of operations herein, for example methods or procedures of the current disclosure, are provided to illustrate aspects of the present disclosure. Operations described herein are schematically described and / or depicted, and operations may be combined, divided, re-ordered, added, or removed in a manner consistent with the disclosure herein. It is understood that the context of an operational description may require an ordering for one or more operations, and / or an order for one or more operations may be explicitly disclosed, but the order of operations should be understood broadly, where any equivalent grouping of operations to provide an equivalent outcome of operations is specifically contemplated herein. For example, if a value is used in one operational step, the determining of the value may be required before that operational step in certain contexts (e.g. where the time delay of data for an operation to achieve a certain effect is important), but may not be required before that operation step in other contexts (e.g. where usage of the value from a previous execution cycle of the operations would be sufficient for those purposes). Accordingly, in certain embodiments an order of operations and grouping of operations as described is explicitly contemplated herein, and in certain embodiments re-ordering, subdivision, and / or different grouping of operations is explicitly contemplated herein.

[0067] The methods and systems described herein may transform physical and / or or intangible items from one state to another. The methods and systems described herein may also transform data representing physical and / or intangible items from one state to another.

[0068] The elements described and depicted herein, including in flow charts, block diagrams, and / or operational descriptions, depict and / or describe specific example arrangements of elements for purposes of illustration.

[0069] While the disclosure has been disclosed in connection with the preferred embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present disclosure is not to be limited by the foregoing examples, but is to be understood in the broadest sense allowable by law.EXAMPLESExample 1: Fabrication and Characterization of Fabric / Silk Fibroin Composites

[0070] Disclosed herein is the analysis of the effect of silk fibroin solution concentration on the properties of fabric / silk fibroin composites. Silk fibroin aqueous solution is employed to perform impregnation of fabrics thus providing advanced properties that enable their use in various fields (e.g., packaging, and single-use plastic replacement). Since the adhesion between the two materials directly affects the properties of the composites, it is crucial to understand the influence of the fabrication conditions and material characteristics on their interaction. In order to do so, the macroscopic and microscopic morphology is characterized quantifying the composite thickness, weight, color and using SEM analysis. The interaction between fabric and silk fibroin as well as silk fibroin secondary structure is examined using FTIR and thermal analysis. The mechanical and barrier properties and the shapeability are carefully evaluated as they represent important parameters to translate the use of fabric in the packaging industry.

[0071] Experimental Methods—Fabric / Silk Fibroin composite fabrication: Regenerated silk fibroin solution is extracted from Bombyx mori cocoons using an established protocol (See Rockwood, D. N.; Preda, R. C.; Yücel, T.; Wang, X.; Lovett, M. L.; Kaplan, D. L. Materials Fabrication from Bombyx Mori Silk Fibroin. Nat. Protoc. 2011, 6 (10), 1612-1631.). Cotton jersey fabric (100% Organic cotton, 190 g / m2, purchased from Organic Cotton Plus, USA) is laser-cut in a square format (5 cm side length). The fabric squares are infiltrated with a constant volume of silk fibroin solutions at various concentrations (i.e., 2, 6, 10, 14, 18, 22 wt. / v %) and let dry at room temperature overnight (FIG. 1).

[0072] Characterization: The weight change of the samples before and after the infiltration with silk fibroin is measured with an analytical balance. The thickness is measured using a micrometer. The color is analyzed collecting images using a scanner and ImageJ to quantify the color in the RGB color space. The morphological characteristics of the composite materials are studied through Scanning Electron Microscopy (SEM).

[0073] The secondary structure of silk fibroin at the surface of the composites is analyzed using Fourier-transform infrared (FTIR). The degradation temperature and glass transition temperature of the composites are determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

[0074] The tensile strength, elongation at break and Young's modulus of the composite materials are evaluated using a Instron tensile testing machine following the ASTM D5035. The stiffness is evaluated by measuring the bending angle of a rectangular strip of material clamped at one end and allowed to overhang and bend under its own weight. The water vapor and oxygen transmission rates are measured following the ASTM E96M and the ASTM F3136 respectively. The macroscopic shapeability is investigated through thermoforming using a hydraulic heat press and vacuum forming. The micro-patternability of the composite materials are evaluated by imprinting a diffraction grating during drying of the composite materials. SEM analysis is used to confirm the pattern transfer.

[0075] Results and expected outcomes: The macroscopic characteristic of materials such as thickness and weight play an important role in the determination of their properties (e.g., mechanical and transport properties) and can influence their applicability in certain fields. Consequently, the effect of silk fibroin solution concentration on the thickness, weight and color of the fabric / silk fibroin composite is analyzed (FIG. 2). The obtained results show that by increasing the concentration on the silk fibroin solution from 2 to 22 wt. / v % the thickness and weight of the composite materials increase and the color shifts from white to yellow, which corresponds to a decrease of the Blue value in the RGB color space. In the context of composites materials, the achievement of a uniform distribution of the different phases is pivotal to ensure that the final composite has uniform properties. SEM micrographs show the uniform distribution of silk fibroin on the surface and bulk of the composites (FIG. 2). An increase in silk fibroin concentration corresponds to an increasing amount of silk fibroin covering the surface of the fibers and filling the space between the fibers and the bundles.

[0076] The presence of silk fibroin on the surface of the composites is further confirmed by FTIR analysis. Given its shallow penetration depth, FTIR analysis is not able to provide information about the secondary structure of silk fibroin in the bulk of the materials which is useful to infer the interaction between silk fibroin and cotton fabric. Additionally, silk fibroin secondary structure is directly correlated to its mechanical and barrier properties. Since several previously reported studies have documented the formation of ß-sheets in silk / cellulose composites, silk fibroin is expected to show a crystalline structure (i.e., ß-sheets) induced by the presence of cotton. Since an increase in the crystallinity of silk fibroin is reported to cause an increase in its glass transition temperature, the glass transition temperature of silk fibroin in the composites can be measured using DSC to overcome the lack of information about the secondary structure of silk fibroin in the composites' bulk. The glass transition temperature of pristine silk fibroin films is 183° C., while it increases to 189° C. for silk fibroin in the composite materials confirming the formation of ß-sheets (FIG. 3). Additionally, TGA analysis reveals an increase in the on-set degradation temperature in the composites compared to the pristine silk fibroin film. Without wishing to be bound by any particular theory, silk fibroin improves the thermal stability of the cotton fabric by creating a layer of char that protects the underlying material. The pristine cotton showed a residual weight of 8%. The residual weight increased by increasing silk fibroin concentration and ranged between 15% and 25% (FIG. 3).

[0077] The tensile test confirms that silk fibroin can be used to modify the mechanical properties of fabric and increase its stiffness. Increasing the concentration of silk fibroin, the Young's modulus of the composites increases, while the elongation at break decreases (FIG. 3). The stiffness of the composites can be evaluated also measuring the bending angle formed with the horizontal plane, which decreases by increasing silk fibroin concentration and demonstrates the ability of the composites to hold a shape (FIG. 4a).

[0078] Without wishing to be bound by any particular theory, the water vapor and oxygen permeability may decrease by increasing the silk fibroin concentration and may be lower compared to the permeabilities of pristine silk fibroin films and pristine fabric. Without wishing to be bound by any particular theory, the interaction between fabric and silk fibroin and the formation of ß-sheets in the silk matrix may increase the barrier properties. Without wishing to be bound by any particular theory, the permeability of fabric may be influenced by the inter-fiber distance within the bundles and the knitting tightness which create voids that allow vapor and gases transport. In the composites, silk fibroin fills those voids thus decreasing the permeability. At the same time, the presence of fabric increases the tortuosity factor for the diffusion of vapor and gas molecules, which reduces the permeability compared to pristine silk fibroin films. The wettability of the composites may be evaluated through contact angle measurements.

[0079] The composites show the ability to hold a wide range of complex shapes (FIG. 4b). Examples can range from more simple ones such as cup-like shapes, to more complex shapes like noodle boxes or corrugated cardboard. Additionally, the surface of the composite can be micro-patterned as shown by the imprinting of a diffraction grating (FIG. 4c). The same approach could be used to increase the hydrophobicity of the composites by transferring a lotus leaf or a gecko feet pattern.

[0080] Without wishing to be bound by any particular theory, there may be an effect of the drying conditions (temperature and R.H.) on the properties of the composite materials. Cotton jersey was chosen since it is one of the most used fabric in the clothing industry, the same approach could be applied to other types of fabric.

[0081] Disclosed herein is information on how to finely modulate the mechanical and barrier properties of fabric to fabricate composite materials with a wide range of compositions and properties. Especially if coupled with post-treatments of silk fibroin (e.g., water annealing or alcohol treatment) and surface patterning, this approach may enable obtaining a library of materials—ranging from soft to stiff, permeable to impermeable and their combinations—that can find application in different contexts.Example 2: Investigation of the Recyclability and Biodegradability of the Fabric / Silk Fibroin Composite Materials

[0082] Disclosed herein is the determination of a recycling process for the fabric / silk fibroin composite materials, its effect on their properties and the analysis of their biodegradability. This disclosure enables the fabrication of composite materials with a completely circular approach. Both the silk fibroin solution and fabric would be obtained from waste, and, after use, they would be recovered and re-used to form new composites. After fabricating the composite materials, silk fibroin may be removed to recover the fabric that will be re-used to fabricate new fabric / silk fibroin composites. Since the ability to withstand the recycling process is crucial for real-life applications (e.g., packaging), the mechanical and barrier properties of the composites are evaluated for affect by the recycling process. Various processes to remove silk fibroin from fabric are tested.

[0083] Experimental Methods: Fabric / Silk Fibroin composite recycling. Cotton jersey fabric squares are infiltrated with silk fibroin solutions (6 wt. / v %) and let dry at room temperature overnight. Two different processes are tested to remove silk fibroin: 1) immersion of the composite materials in DI water during 8 h under stirring; and 2) Infiltration of the composite materials in a lithium bromide aqueous solution (9.3 M) during 4 h at 60° C. followed by rinsing in DI water. Such fabrics are then infiltrated with silk fibroin solutions (6 wt. / v %) and let dry on a silicone mat at room temperature overnight. This process (infiltration-removal-infiltration) is named ‘recycling cycle’ and is repeated up to 5 times.

[0084] Characterization: The weight of fabric before and after the infiltration with silk fibroin as well as after its removal is measured using an analytical balance. After each recycling cycle, the tensile strength, elongation at break, Young's modulus, water vapor and oxygen transmission rates of the recycled composite materials are evaluated.

[0085] Results and expected outcomes: Silk fibroin removal through water immersion shows unsatisfactory results. After immersion, the composite materials lose just 2% of their weight, which corresponds to an incomplete removal since the solid content of silk fibroin in the composites is 17%. Silk fibroin has good solubility in water when amorphous, while it becomes insoluble in water when its crystalline (e.g., after the formation of ß-sheet secondary structure). Without wishing to be bound by any particular theory, the poor solubility of silk fibroin in the composites suggest the formation of a crystalline structure based on the reported interaction between silk fibroin and cellulose as well as on the analysis of the glass transition temperature.

[0086] The second approach, which relies on the dissolution of silk fibroin in a LiBr solution, enables the complete removal of silk fibroin. The mechanical properties of the composite are evaluated after 1 to 5 recycling cycles (FIG. 5). The tensile strength is not affected by the recycling process. After an initial variation following the first recycling cycle, the elongation at break and Young's modulus are not affected by the recycling process. The moderate increase in Young's modulus and decrease in elongation after the first recycling cycle suggest a stiffening of the composites which can be attributed to an accumulation of a residue of silk fibroin in the material bulk. The minimal effect of the recycling process on the mechanical properties of the material indicates its promising potential for recycling.

[0087] Based on this result, and without wishing to be bound by any particular theory, the water vapor and oxygen permeability may not be affected by the recycling process. In some embodiments, a minimal accumulation of silk fibroin in the material bulk can further reduce the porosity and lead to improved barrier properties.

[0088] To optimize recovery of silk fibroin from the composite materials and re-use it to make new composites, a minimum volume of LiBr solution to dissolve silk fibroin and a minimum volume of water may be used for rinsing. The molecular weight of the recovered silk may be measured, and the variation of its properties may be investigated. Since the dissolution in lithium bromide should not alter the molecular weight, the properties of silk may not be undermined by the recycling.

[0089] In some embodiments, after rinsing the composite materials, the concentration of silk fibroin in water may be low and the protein could undergo gelling soon after the dialysis (needed to remove the LiBr used for silk fibroin removal from fabric) or during concentration steps. Such silk fibroin gels could be solidified and the silk solids could be dissolved, and the obtained solution could be used to develop new composites. Additionally, the silk solids could become a resource for other applications.Example 3: Functionalization of Fabric / Silk Fibroin Composite Materials to Confer Sensing Properties

[0090] Disclosed herein is the functionalization of fabric / silk fibroin composite materials to impart sensing properties using colorimetric sensing inks which are printed either on fabric before the infiltration with silk fibroin or directly on the composite materials. This disclosure enables the fabrication of sensing composite materials that can be relevant in the packaging industry. Such made sensing packaging would ensure the optimal storage conditions of delicate products. This approach could be extended to various types of colorimetric sensors. As an example, colorimetric sensing could be coupled with packaging to detect food spoilage.

[0091] Sensing ink fabrication: Temperature sensing inks may be fabricated mixing a thermochromic pigment together with a mixture of alginate solution, silk fibroin solution, a thickening agent and fixer. pH sensing inks may be fabricated mixing a pH indicator (nitrazine yellow, phenol red or bromocresol green sodium salt) together with a mixture of alginate solution, silk fibroin solution, a thickening agent and fixer. Cold chain monitoring sensors may be fabricated by functionalizing one side of a fabric strip with a pH sensing ink and, once dry, impregnate the other side with a citric acid solution (pH 3) before storing the strip in the freezer at −20° C. Oxygen sensors may be fabricated under nitrogen atmosphere by mixing in a silk fibroin solution (4 wt. / v %): chromogenic substrates (3,5-dichloro-2-hydroxybenzenesulfonate, 4-aminoantipyrine, acid yellow), enzymes (horseradish peroxidase (HRP) and lactate oxidase (LOx)) and lactic acid. The formulation of this mixture has been previously tested to fabricate printable lactate sensing wearable patches. The mixture is then converted into a hydrogel using acetone. Finally, acetone is removed to obtain an oxygen-sensing hydrogel.

[0092] Characterization: To characterize the colorimetric response of the temperature, cold chain, pH and oxygen sensors, they may be exposed to increasing temperature, pH and oxygen concentration respectively, wherein a response is recorded acquiring images with a camera. The images are then analyzed using ImageJ to quantify the color variation in the RGB color space.

[0093] Results and expected outcomes: The temperature sensing inks are reversible inks that can be used in various contexts since, by varying the thermochromic pigment, it is possible to vary the sensing range. For example, one ink may change color from grey to transparent at temperatures between 70 and 75° C. and can be applied in the context of temperature monitoring for hot beverages and foods (FIG. 6a). In fact, hot beverages (e.g., tea or coffee) are normally served at temperature above 70° C. which can cause thermal injury to the tongue and esophageal mucosa. Such sensors can be applied on food containers to indicate when the content can be safely consumed without causing injuries.

[0094] Cold chain monitoring sensors can be used to monitor temperature-sensitive products (e.g., pharmaceuticals, biologics, food) which need to be transported at subfreezing temperatures since suboptimal conditions during transport and storage can damage their quality (FIG. 6b). When removed from the freezer, the citric acid solution travels along the fabric strip and reacts with the pH sensing ink causing a color change from blue to yellow in the central part of the fabric strip. The response time may be evaluated by exposing the sensors to increasing temperatures. Additionally, the response time may be modulated by varying the length of the fabric strip to obtain a faster or slower colorimetric response.

[0095] Oxygen sensors can be used to ensure the optimal storage conditions of products that need to be stored under modified atmosphere (i.e., certain medical devices and meat products) (FIG. 6c). The oxygen sensors may be based on the LOx / HRP cascade reaction. In the presence of oxygen, (lactate oxidase) LOx oxidizes lactate to produce pyruvate and hydrogen peroxide, which is used by (horseradish peroxidase) HRP to oxidize the chromogenic substrates generating a visible color change from yellow to red. While being under nitrogen atmosphere, the colorimetric reaction cannot happen, and the sensor is yellow. When entering in contact with air, the sensor turns red. In this context, silk fibroin may act as a stabilizing agent for the enzymes used for detection and increase the shelf-life of the sensors. The detection limit, sensitivity and stability will be evaluated by recording the color variation while exposing the sensor to increasing concentrations of oxygen.

[0096] In embodiments, since the oxygen sensors are fabricated in a hydrogel format (since they do not show a colorimetric response in a dry state), a hygroscopic component (e.g., glycerol) may be added to the formulation to keep the sensor moist.Example 4: Twill & Silk Fibroin Composites: Mechanical Properties

[0097] Referring to FIG. 7A and FIG. 7B, an increase in silk fibroin solution concentration corresponds to a linear increase in Young's Modulus (FIG. 7B). Using twill, which is a woven fabric used commonly to create strong fabrics (e.g., denim), or other woven fabrics including fabrics generated using the warp / weft style of weaving, as a starting material yielded composites with higher tensile strength (FIG. 7A). FIG. 7C depicts twills with various increasing silk fibroin concentrations that resulted in the data presented in FIG. 7A and FIG. 7B. FIG. 8 depicts a mechanical characterization (Youngs modulus [GPa] vs / Tensile strength [Mpa]) of various materials including cotton jersey (e.g., knitted fabric commonly used to create stretchy fabrics (e.g., t-shirts)), elastomers, silk foam, polymers, metals, non-technical ceramics, foams, and twill-silk fibroin composites. FIG. 9A shows that an increase in silk fibroin solution concentration corresponds to a decrease in bending angle (e.g., increased stiffness), with FIG. 9B presenting images of the materials tested in FIG. 9A. Twill and silk fibroin composites exhibit shapeability in terms of folding (e.g., to form takeout containers), thermoforming (e.g., to form bowls, plates, etc.), and combinations thereof. Twill and silk fibroin composites can form articles with twill multilayers, such as utensils, eyewear, and the like.

Claims

1. A method of making a fiber-reinforced polymer composite comprising a cured silk polymer matrix having a woven, non-woven, or knitted fabric embedded therein, the method comprising:a) impregnating a woven, non-woven, or knitted fabric with a silk fibroin solution;b) curing the silk fibroin solution, thereby forming the cured silk polymer matrix having the woven, non-woven, or knitted fabric embedded therein,wherein the fiber-reinforced polymer composite comprises the cured silk polymer matrix in an amount by weight that is at least 25%, at least 50%, at least 75%, or at least 100% of the woven, non-woven, or knitted fabric,wherein the cured silk polymer matrix comprises silk fibroin in an amount by weight of at least 10%.

2. A method of making a fiber-reinforced silk polymer composite comprising a cured silk polymer matrix impregnating a woven, non-woven, or knitted fabric substrate, the method comprising:a) impregnating the woven, non-woven, or knitted fabric substrate with a silk fibroin solution, the woven, non-woven, or knitted fabric substrate having a native porosity of at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%;b) curing the silk fibroin solution, thereby forming the cured silk polymer matrix within pores of the woven, non-woven, or knitted fabric substrate and producing the fiber-reinforced silk polymer composite,wherein the fiber-reinforced silk polymer composite has a composite porosity that is at least 50% less than the native porosity of the woven, non-woven, or knitted fabric substrate,wherein the cured silk polymer matrix comprises silk fibroin in an amount by weight of at least 10%.

3. The method of claim 2, wherein the silk fibroin solution comprises silk fibroin in an amount by weight of between 0.1% and 30%.

4. The method of claim 2, wherein the woven, non-woven, or knitted fabric substrate and the silk fibroin solution are in a mold having a negative imprint of a shape during the curing of step b), the fiber-reinforced silk polymer composite thereby taking a solid form comprising at least a portion of the shape.

5. (canceled)6. The method of claim 4, wherein the mold has a negative imprint of a micropattern, thereby providing the micropattern on at least a portion of a surface of the fiber-reinforced silk polymer composite.

7. The method of claim 2, wherein the impregnating of step a) is performed at an impregnating pressure of between 0.1 atm and 20 atm, between 0.2 atm and 10 atm, or between 0.5 atm and 5 atm, or at an impregnating pressure of 1 atm and / or at an impregnating temperature of between 4° C. and 50° C.

8. (canceled)9. The method of claim 2, wherein the curing of step b) is performed at a curing pressure of between 0.1 MPa and 50 MPa and / or at a curing temperature of between 18° C. and 250° C. and / or at a curing relative humidity of between 0% and 90%.

10. (canceled)11. (canceled)12. The method of claim 2, wherein the curing of step b) comprises drying at a curing temperature of between 100° C. and 150° C., a curing pressure of between 20 MPa and 30 MPa, and a curing relative humidity of between 20% and 40%.

13. The method of claim 2, the method further comprising micropatterning the fiber-reinforced silk polymer composite.

14. The method of claim 2, the method further comprising affixing an embedded functional sensing spot to the woven, non-woven, or knitted fabric substrate prior to impregnating.

15. The method of claim 14, wherein the affixing the embedded functional sensing spot comprises printing the embedded functional sensing spot from an embedded functional sensing ink.

16. The method of claim 2, the method further comprising affixing an exposed functional sensing spot to the fiber-reinforced silk polymer composite.

17. The method of claim 16, wherein affixing the exposed functional sensing spot comprises printing the exposed functional sensing spot from an exposed functional sensing ink.

18. (canceled)19. A fiber-reinforced silk polymer composite comprising:a woven, non-woven, or knitted fabric substrate having a native porosity of at least 50%, at least 60%, at least 70%, at least 80%, or at least 90%;a cured silk polymer matrix impregnating the woven, non-woven, or knitted fabric substrate,wherein the cured silk polymer matrix comprises silk fibroin in an amount by weight of at least 10%,wherein the fiber-reinforced silk polymer composite has a composite porosity that is at least 50% less than the native porosity of the woven, non-woven, or knitted fabric substrate.20-23.

24. The method of claim 2, wherein the fiber-reinforced silk polymer composite has a thickness of between 0.1 mm and 5 mm.

25. The method of claim 2, wherein the fiber-reinforced silk polymer composite has a tensile strength of between 2 MPa and 80 MPa.

26. The method of claim 2, wherein the fiber-reinforced silk polymer composite has an elongation at break of between 0.1% and 800%.

27. The method of claim 2, wherein the fiber-reinforced silk polymer composite has a Young's modulus of between 0.5 MPa and 20 GPa.

28. The method of claim 2, wherein the fiber-reinforced silk polymer composite has a

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